Vacuum packaging of perishable food products is common. Vacuum packaging typically consists of enveloping the food (product) in a bag generated from a film tube in a horizontal packaging machine. The generated bag comprises a closed end and an opposite open end. The bags are then conveyed to a vacuum station where the bags are introduced in a vacuum chamber to complete the packaging.
In the packaging machine, the bags are generated one after the other in a longitudinal forward movement direction. The packaging machine comprises actuation means acting on the film tube containing products therein distributed in the forward movement direction in order to generate a transverse cut in the film tube and a complete transverse seal on one of the sides of the transverse cut. A bag is therefore separated from the rest of the film tube with a single operation (with the transverse cut), and depending on the side of the transverse cut on which the transverse seal is made, one end of said bag is left open and one end of the next bag to be generated is closed (with the transverse seal), or one end of said bag is closed (with the transverse seal) and one end of the next bag to be generated is left open, improving the productivity of said machine.
In the vacuum chamber, air is discharged from inside the bags through their open end and said open ends are then hermetically closed or sealed, generating independent closed packages comprising a vacuum packed product. The productivity of the packaging machine as mentioned has been improved, so the vacuum chamber operating time is usually longer than the time the packaging machine needs to generate bags with at least one product therein, the vacuum chamber therefore being an element slowing down the production rate in the complete packaging process.
Solutions to this problem by means of installations comprising a set of rotary vacuum chambers such as those disclosed, for example, in patent document U.S. Pat. No. 4,640,081A, are known in the state of the art. Such installations comprise a horizontal packaging machine as well as a plurality of vacuum chambers which, by means of the rotation of said vacuum chambers, receive the corresponding bag from the packaging machine to remove air from inside same and to seal the opening of the package. However, due to their configuration, such installations require a considerable size and thorough maintenance.
Patent document US20050178090A1 does not have rotary vacuum chambers. This patent document describes a vacuum packaging installation comprising a plurality of vertically arranged vacuum chambers. Hermetically closed bags loaded with two products therein are formed before the vacuum chamber in a horizontal packaging machine, and they are then longitudinally conveyed to the vacuum chamber. The vacuum chamber comprises a sealing tool arranged transverse to the product feeding direction, which is arranged around the bag, between the two products. The sealing tool makes a transverse cut between both products splitting the package into two independent bags with a product inside each bag and with one opening at one end of each bag. Air is removed from inside the bags through the openings and they are then hermetically sealed, both vacuum packed products being in individual packages. Since there is more than one vacuum chamber, while the packaging operation is being performed in one of them, the other can be loaded, therefore improving productivity.
Such installations, however, involve using a plurality of vacuum chambers if productivity is to be improved, making the installation more expensive. Furthermore, the vacuum chambers are complex since they have to carry out other tasks such as receiving a bag after performing a circular path or cutting the package in half, which entails a complex and more expensive installation as well as a more thorough maintenance.
To prevent these drawbacks, other solutions using conventional vacuum chambers 800 which are simpler and more cost-effective, such as those shown, for example, in the packaging installation 1000″ depicted in FIG. 1, are known. Such vacuum chambers 800 comprise a sealing tool 801 that extends longitudinally in the vacuum chamber 800 and is suitable for closing the openings of the bags 1″ with products P″ which are generated by a horizontal packaging machine 100″ and introduced in the vacuum chamber 800, after removing air from inside same. Therefore, increasing the capacity of the vacuum chamber 800 itself (its size and the longitudinal size of the sealing tool 801) to enable housing a larger number of bags 1″ is sufficient to increase productivity. In the packaging installations 1000″ of the type shown in the example of FIG. 1, the opening of the bags 1″ must be suitably oriented with respect to the sealing tool 801, for which the bag 1″ is generally rotated 90° when the vacuum chamber 800 is arranged parallel to the longitudinal forward movement direction of the packaging machine 100″, or the bags 1″ are fed transverse to the vacuum chamber 800 when said vacuum chamber 800 is arranged perpendicular to the forward movement direction of the packaging machine 100″ by means of suitable conveyance means 805 (configuration shown in FIG. 1). The bags can gradually accumulate at the inlet of an accumulator 804, forming a line L″. With this solution, installation complexity is simplified and its cost reduced, while at the same time its productivity can be increased.
Based on this vacuum chamber design, in order to at least make use of the described advantages, solutions increasing the capacity of vacuum chambers without excessively increasing their cost or complexity, and without excessively increasing their size, are also known. One example is shown in the packaging installation 1000′ depicted by way of example in FIG. 2. The vacuum chamber 900 of said installation is fed with two lines L1′ and L2′ of bags 1′ parallel to one another and generated in a packaging machine 100′, and it comprises a longitudinal sealing tool 901 for each line L1′ and L2′. The sealing tools 901 are arranged at the transverse ends of the vacuum chamber 900, such that the openings of each pair of parallel bags 1′ with products P′ reaching the vacuum chamber 900 of lines L1′ and L2′ are arranged for being actuated by the corresponding sealing tools 901 of the vacuum chamber 900, said pairs of bags 1′ being oriented at 180° with respect to one another (i.e., the open or closed ends of both bags 1′ are facing one another).
In these installations, the products leave the horizontal packaging machine 100′ one by one towards the vacuum chamber 900, in a linear manner, loaded in bags with an opening at one of the ends thereof. All the bags loaded with products leave the packaging machine 100′ with the same orientation, such that the installation comprises means for suitably orienting said bags for their introduction in the vacuum chamber 900.
When the vacuum chamber 900 is arranged parallel to the forward movement direction of the packaging machine (a situation not shown in the drawings), said means comprises a rotating device for rotating the bags 90°, and a divider generating two parallel lines of bags. The rotating device causes a bag to rotate 90° in one direction and arranges it in one of the lines, and the next bag to rotate 90° in the opposite direction and arranges it in the other line. Once these two bags are arranged in the two lines (with the closed ends facing one another), both lines of the divider are made to move forward in order to move said bags closer to the vacuum chamber and make room for two new bags.
When the vacuum chamber 900 is arranged perpendicular to the forward movement of the packaging machine 100′ as shown by way of example in FIG. 2, the means for suitably orienting the bags comprises a divider 902 which alternately directs the bags coming from the packaging machine 100′ to two different paths 905a and 905b, such that the bags reach a feeder 903 of the sealing station after travelling different paths 905a and 905b. Each path 905a and 905b suitably orients the corresponding bags: path 905a maintains the orientation it has at the outlet of the packaging machine 100′, and path 905b causes the bags to rotate 180°. Therefore, in the feeder 903, bags coming from the path 905a are arranged in line L1′ and bags coming from the other path 905b are arranged in the other parallel line L2′, and said feeder 903 feeds the bags in twos to an accumulation belt 904 before the vacuum chamber 900, so that once a given number of bags have accumulated on the accumulation belt 904, they are introduced in the vacuum chamber 900.
Such installations therefore allow increasing installation productivity by increasing the vacuum chamber packaging capacity.